I changed oil at 16k miles, basically twice a year. M1 0W/40 European Blend/factory fill. Typically added 1 qt after 8k miles. Tested it once, lab said I could extend the interval out further. Chose not to.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)